Vulnerability in Node-Oauth Node-Oauth2-Server
CVE-2026-41213
@node-oauth/oauth2-server is a module for implementing an OAuth2 server in Node.js. The token exchange path accepts RFC7636-invalid code_verifier values (including one-character strings) for S256 PKCE flows. Because short/weak verifiers are accepted and failed verifier attempts do not consume the authorization code, an attacker who intercepts an authorization code can brute-force code_verifier guesses online until token issuance succeeds.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.003 (26.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 27th percentile — 26.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: +0.001
Affected products
- Node-Oauth Node-Oauth2-Server — versions < 5.3.0
- Node-Oauth Node-Oauth\/oauth2-Server
Weakness classification (CWE)
References
- github.com/node-oauth/node-oauth2-server/security/advisories/GHSA-jhm7-29pj-4xvf (Exploit, Mitigation, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-41213?
- CVE-2026-41213 is a medium-severity vulnerability in Node-Oauth Node-Oauth2-Server, classified under Improper Restriction of Excessive Authentication Attempts. CVSS score: 5.9/10. Published 2026-04-23.
- How severe is CVE-2026-41213?
- Medium severity. CVSS v3 base score is 5.9 out of 10.